A state function used in advanced mechanics to derive the equations of motion for complex systems. It is calculated by taking the total kinetic energy of the system and subtracting the total potential energy. Formulating a problem this way allows engineers to solve multi-body dynamics, like robotic manipulators or complex suspensions, without having to track all the internal reaction forces.
Heard on the job
Formulating the Lagrangian for this four-bar linkage is much faster than doing the free body diagrams for every joint.